The use of sulfated and/or sulfonated alkyl phenol ethoxylates in acid galvanic zinc baths is known according to DE OS No. 32 48 503. Such baths have the disadvantage that a disturbing foam layer is developed when air is bubbled therethrough, thereby preventing a perfect deposition of zinc on the substrate (e.g. ferrous metal substrate).
The use of polyoxylated naphthols in combination with anionic sulfonic acid condensation products and sulfonic acids, as well as with nonionic sulfonic acid condensation products, is also known from U.S. Pat. No. 4,075,066. These zinc baths have the disadvantage that the turbidity temperature decreases in the course of processing and must then be increased by large doses of selected wetting agents.